Implantable medical devices for treating irregular contractions of the heart with electrical stimuli are known. Exemplary implantable devices are defibrillators and pacemakers. Various types of electrical leads for defibrillators and pacemakers have been suggested, many of which are placed transvenously. Such leads are introduced into the patient's vasculature at a venous access site and travel through veins to the sites where the leads' electrodes will be implanted or otherwise contact target coronary tissue. Electrodes for transvenously-placed leads can be implanted in the endocardium (the tissue lining the inside of the heart) of the right atrium or ventricle, or alternatively, in the branch vessels of the coronary venous system. In particular, lead electrodes can be implanted in the coronary sinus or a branch vessel thereof for sensing and/or stimulation of the left side of the heart (i.e., the left ventricle).
Various techniques have been used to facilitate fixation of the foregoing types of leads at the desired implantation sites. For leads partially implanted within the coronary venous system, fixation techniques should provide fixation sufficient to secure the lead in the desired implanted position, both acutely and chronically, without impeding delivery of the lead to the implantation site.
There is thus a need in the art for a device and method for fixation of cardiac leads within the coronary vasculature which does not interfere with delivery of the lead and which can be deployed after delivery to provide acute and/or chronic fixation.